Absence of EOGT Precludes Defective Development in Fringe-null Mouse Intestine

Identifying biological roles for glycosyltransferases is a continuing challenge and important for defining morbidities associated with congenital disorders of glycosylation. Here we investigate the consequences to intestinal development of conditionally deleting Lfng alone or Lfng, Mfng and Rfng together in a mixed or Eogt-null genetic background. Each Fringe transfers N-acetylglucosamine (GlcNAc) to fucose (Fuc) attached to Ser or Thr by POFUT1 in a consensus sequence found in certain epithelial growth factor-like (EGF) repeats. EOGT transfers GlcNAc directly to Ser/Thr in a separate consensus sequence of the EGF repeat. Notch receptors and Notch ligands contain the largest number of EGF repeats with consensus sites for these O-glycans. Conditional deletion of Pofut1 in mouse intestine causes similar developmental defects to deletion of Notch1 and Notch2 or Dll1 and Dll4. LFNG also contributes to optimal Notch signaling in mouse intestine. In this work, we generated Lfng[F/F]:Villin-Cre and Lfng[F/F]Mfng[-/-]Rfng[-/-]:Villin-Cre mice in which extension of O-Fuc on EGF repeats was inhibited or prevented in intestinal epithelium. Conditional deletion of either Lfng alone or all three Fringe activities together led to defective intestinal development with a marked increase in goblet and Paneth cells, increased crypt width and reduced villus length. Unexpectedly, in mice globally lacking EOGT, conditional inactivation of the three Fringe genes did not lead to defective intestinal development. Thus, the absence of EOGT prevented disruption of development in Fringe-null intestine, identifying a novel role for EOGT in regulating intestinal development.